Apparatus for stacking sheets



Sept. 18, 1962 c. G. JOA

APPARATUS FOR STACKING SHEETS 3 Sheets-Sheet 1 Filed Aug. 19, 1960 M1,, AMAM A TraeA/svs Sept. 18, 1962 c. G. JOA

APPARATUS FOR smcxmc; SHEETS 3 Sheets-Sheet 2 Filed Aug. 19, 1960 BY 4%, myw

3 Sheets-Sheet 3 C. G. JOA

APPARATUS FOR STACKING SHEETS HIP Sept. 18, 1962 Filed Aug. 19, 1960 INVENTOR.

3,054,516 APPARATUS FOR STACKING SHEETS Curt George Joa, Box 1121, Ocean Ridge, Fla. Filed Aug. 19, 1960, Ser. No. 58,788 2 Claims. (Cl. 214-6) This invention relates to an apparatus for stacking sheets.

The invention will be exemplified in an apparatus embodiment thereof particularly adapted to stack folded paper tablecloths. It is clear, however, that the invention is not thus limited and may be embodied in machines to stack any material in sheet form.

The present invention includes apparatus for metering the sheets into a stack and counting the sheets as they are being metered. After a predetermined number of sheets have been stacked, suitable mechanism is triggered to transfer the stack to a discharge conveyor.

The novel apparatus of the present invention for metering the discrete sheets into a stack includes a metering table consisting of plates which reciprocate in their own plane towards and away from each other as part of a cycle of operation of the stacker. Each sheet is momentarily marginally supported on the opposed margins of the adjacent plates. The plates are then retracted to permit the sheet to drop by gravity therebet-ween onto a collecting apron below the table. As each sheet is metered through the space between the plates, a counter is actuated to log the number of sheets deposited in the stack. When a predetermined number of sheets have been stacked, mechanism is actuated to transfer the stack onto a discharge conveyor and the cycle repeats itself indefinitely.

The counting mechanism desirably comprises a photoelectric cell which faces a non-reflective target on one of the retractable plates. When a sheet of light reflective material is interposed between the light cell and the target, the cell will be triggered to actuate both the counting mechanism and the mechanism for retracting the plates to release the sheet.

In order to facilitate transfer of the stack from the collecting apron to the discharge conveyor, the apron is desirably at a slightly higher level than the discharge conveyor, thus to permit shifting the stack to a position above the level of the discharge conveyor before lowering it thereonto for smooth transfer from the apron to the conveyor. The apron and conveyor have portions which are interleaved to facilitate transposition of the levels of the apron and discharge conveyor.

Other objects, features and advantages of the invention will appear from the following disclosure in which:

FIG. 1 is a plan view of a stacking machine embodying the present invention.

FIG. 2 is a side elevation of the machine of FIG. 1.

FIG. 3 is a fragmentary side elevation similar to that shown in FIG. 2, but showing a stack in the course of transfer to the discharge conveyor.

FIG. 4 is a fragmentary perspective view of a stacking machine embodying the invention. This figure diagrammatically illustrates flow of sheets through the stacking machine.

FIG. 5 is a schematic diagram indicating the pneumatic and electrical connections by which the operation of the machine is controlled.

FIG. 6 is an end view taken along the line 66 of FIG. 1.

FIG. 7 is a cross section taken along the line 7-7 of FIG. 1.

FIG. 8 is a cross section taken along the line 8-8 of FIG. 1.

FIG. 9 is a cross section taken along the line 9-9 of FIG. 1.

, 3,054,516 Patented Sept. 18, 1962 Stacking machines embodying the present invention are adapted to receive sheet material such as folded paper tablecloths '15 from a belt conveyor 16 or the like. As best shown in FIGS. 1 and 2, the stacking machine is mounted on legs 17 which support longitudinal channelshaped frame members 18. The channels 18 support on posts 19 upper level channel supports 20 having paired cross rail members 21, 22. The respective pairs of cross rails 21, 22 support respective sets of longitudinally disposed guide rods 23, 24. Rod sets 23, 24 each provide guide and support means for bearing blocks 27, 28 from the undersurfaces of which project towards each other reciprocating metering table plates 29, 30.

The plates 29, 30 are made to reciprocate towards and away from each other by a pneumatic or like fluid operated motor 31. Motor piston 32 is connected through an adjustable coupling 33 near one end of one arm of a double armed crank 34 pivoted at its mid point on pin 35 to a strap bracket 38. Bracket 38 is mounted at opposite ends to proximate cross rails 21, 22.

The ends of the crank 34 remote from pivot pin 35 are respectively connected on links 39, 40 and corresponding pins 41, 42 to the respective bearing blocks 27, 28 for the metering plates 29, 30. Accordingly, extension of the piston 32 of the pneumatic motor 31 will rotate the crank 34 to retract the plates 29, 36 away from each other.

Each discrete sheet 15 is discharged from the input conveyor 16 onto the proximate margins of plates 29, 30. At this point in the cycle of the stacker, the plate margins will be adjacent one another, the piston 32 having been retracted fully within the motor cylinder 31. This is illustrated in FIG. 4 in which the tablecloth sheet 15 is moving in the direction of arrow 43. The sheet 15 is ordinarily sufficiently stiff to be supported marginally, the central portion of the sheet being unsupported.

The air cylinder 31 is triggered by deposit of the sheet 15 on the plates 29, 30 by reason of the interposition of the sheet between photocell 44 and a non-reflective target 45 on plate 29. Ordinarily a light source 48 beams its light on the non-reflective target so that no light is reflected to the photocell 44. However, when a sheet 15 having a reflective surface is placed over target 45, the beam of light from source 48 will be reflected thereby to the photoelectric cell 44, thus to complete a circuit to the photocell relay 49 shown in FIG. 5 and trigger the control relay 54 which actuates solenoid 51 connected to a three-way valve 52 in the air line 53- which supplies the pneumatic cylinder 31. Actuation of the air cylinder 31 as aforesaid will extend its piston 32 to separate the plates 29, 30 as aforesaid and permit the sheet to drop by gravity between the margins of the retracting plates 29, 30 onto a collection apron 54. The apron 54 desirably consists of a series of laterally spaced longitudinally disposed strips 55, which may conveniently be T-shape in cross section, each pivotally connected to a rock shaft 56 supported on brackets 57 from the cross member 58 of the machine frame.

In the course of its retracting or separating movement of the plates 29, 30, bearing block 28 on plate 30 will ultimately engage a reversing switch 59 mounted on cross rail 22. Switch 59 functions through control relay to reverse solenoid 51 and thus reverse the position of the three-way valve 52 to retract piston 32 and to restore the plates to their FIG. 1 position, thus to position them to receive the next sheet 15 in the cycle of the machine.

The collection apron 54 is desirably provided with vertical guide strips 61 against which the leading edges of the sheets are aligned in the course of piling up into a stack 62. Transfer mechanism to transfer the stack onto a discharge conveyor 81 after a predetermined number of sheets has been metered onto the stack includes a pusher' plate 63 supported on paired push beams 64. The push beams 64 have bearing base portions 65 bored to receive guide rods 66 on which the beams are adapted to reciprocate. Corresponding ends of the rods 66 are connected to a transverse channel member 58 and opposite corresponding ends thereof are supported on transverse channel 67.

The respective portions'65 of the push beams 64 are interconnected by a depending bracket 70 to which piston 71 of the pneumatic cylinder 72 is connected for actuating the push beams.

As the photocell relay 49 is triggered by the photocell 44, impulses communicated to the control relay 50 actuate a counter 73 which may conveniently comprise a conventional stepping switch or the like. After a predetermined number of impulses have been counted by the counter, thus indicating a predetermined number of sheets in the stack 62, counter 73 triggers relay 74 to actuate solenoid 75 to turn three-way valve 76 which is in the air line 53 to the air cylinder 72, thus to move the pusher plate 63 in the direction of arrow 77 in FIG. 3 and push the stack 62 off of the apron 54 and onto the laterally spaced belts 80 of a discharge conveyor 81 travelling in the direction of arrow 82 (FIG. 3). The conveyor 81 transports the stack to a carton filling machine or the like for further processing of the stack. 7

' As best shown in FIG. 8, strips 55 of the apron 54 are normally supported at a level higher than the belts 80. Accordingly, as the push plate 63 moves the stack 62 toward the discharge conveyor, the stack will be above the level of the belts to avoid contact of the belts with the stack until the stack is in readiness to be lowered onto the belt conveyor. The structure is such, however, that near the end of the stroke of the push plate 63, apron strips 55 are lowered to a level below the level of the belts 80, as indicated in dotted lines in FIG. 8, so as to transpose the level of the strips and belts. Accordingly, the entire load of the stack 62 is transferred to the belts 80, which carry the stack away.

Transpostion of the level of the apron strips and belt is accomplished by reason of the structure best shown in FIG. 6. Apron 54 has support tracks 83 which ride on rollers 84 carried on bearing stems 85 from the bearing portions 65 of the push beams 64. As is best shown in FIGS. 3 and 4, the tracks 83 are tapered near their end portions 87 so that as the rollers 84 come adjacent the tapered portions 87 of the tracks, the apron will be lowered as aforesaid to transfer stack 62 onto the belt conveyor. discharge.

In order to recycle the push plate 63, there is provided a reversing switch 86 (FIGS. 3 and for the solenoid relay 74. This switch is actuated by a striker 90 mounted on the bracket 70 so that on the completion of the retractive stroke of the piston 72 and deposit of stack 62 on discharge conveyor 80, reverse switch 86 will be actuated to reverse the three-way valve 76 and restore the pressure plate 63 to its retracted position as shown in FIG. 2.

Accordingly, the stacker and transfer mechanism will cycle in response to the deposit on the metering table 29, 30 of sheets 15 which will be counted by the counter 73 as they are successively metered past the plates 29, 30 into a stack 62. When a predetermined number of sheets have been collected on the apron 54, push plate 63 will transfer the stack onto discharge conveyor 80 and will return to be disposed behind a newly formed stack.

What is claimed is:

1. A sheet stacker adapted to receive and stack sheets fed thereto by an input conveyor, said stacker comprising a metering table substantially aligned with the input conveyor to receive discrete sheets therefrom, an apron beneath the metering table and to which sheets are delivered by gravity from the metering table in vertically stacked relation, a discharge conveyor for removing from the apron sheet stacks, said metering table comprising plates and means mounting said plates for movement toward and away from each other, said plates together constituting a sheet support when they are adjacent one another and which will drop said sheets therebetween when they are moved away from one another and a counter responsive to operation of said plate in the course of metering sheets to the apron for counting the number of sheets thus meter-ed, and means actuated by the counter for transferring the stack from the apron to the discharge conveyor, said metering table further comprising a frame, means on said frame on which said plates are mounted for reciprocation, a motor for reciprocating the plates and sensing means responsive to deposit on said plates of a sheet for actuating the motor to retract the plates one from another whereupon the sheet drops by gravity onto the apron, said sensing means comprising a photoelectric cell, one of said plates having a non-reflective target towards which said photocell is aimed, the interposition of arefiective sheet between the cell and the target triggering the cell for actuation of the motor.

2. In a device of the character described, a stack transfer mechanism comprising an apron on which a stack is formed, a discharge conveyor adjacent thereto and transfer mechanism for transferringthe stack from the apron to the discharge conveyor, said apron being normally disposed at a level higher than the level of the discharge conveyor whereby the discharge conveyor will not interfere with movement of the stack thereover, and means for transposing the levels of the apron anddischarge conveyor in the course of stack transfer to shift the stack from the apron to the discharge conveyor, said apron and discharge conveyor having portions which are interleaved to facilitate transposition of the levels thereof, said apron comprising laterally spaced strips, said discharge conveyor comprising laterally spaced belts disposed bewill descend by gravity when said wheels reach said inclined portion of the track as the transfer mechanism moves toward said other end'of the apron, thus to lower said strips with respect to the level of said belts.

References Cited in the file of this patent UNITED STATES PATENTS 1,688,219 Williams Oct. 16, 1928 2,606,483 Forbes Aug. 12, 1952 2,623,587 Hervey Dec. 30, 1952 2,679,789 Graves June 1, 1954 

